Analytical apparatus for determination of sulfur



April 7, 1953 H. 'J. KUSA ANALYTICAL APPARATUS FOR DETERMINATION OF SULFUR Filed Sept. 21, 1950 COMBUSTION PU RNACE VACUUM EXHAUST (I:

kl LINE f SUPPLY INVENTOR. Hf/YPYJ A UJA Patented Apr. 7, 1953 ANALYTICAL APPARATUS FOR DETERIVHNA- TION OF SULFUR Henry J. Kusa, Maple Heights, .Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio Application'september 21, 1950, Serial No.'186,0.70

'5 Claims. (Cl. 219--) In prevalent procedures for determining sulphur, and particularly where the sample is a liquid, such as a petroleum product, a particular disadvantage has been the'great length of time required. And, where the sample is liquid and must be vaporized in a combustion boat, great care has been necessary in order to apply the heat controlledly such as to avoid flashing, boil-over, or spattering on the walls of the tube in which the boat is heated. This has necessitated close attention by a skilled analyst, and has correspondingly been wasteful of time desired for other activities. In accordance with the present invention it now becomes possible to obviate such 'dimculties, and sulphur determinations may be made quickly and precisely. By elimination also oi. flashing and spattering, greater uniformity and reproducibility of results is made possible. Other objects and advantages will appear from the following description.

'To the accomplishment of the foregoing and :related ends, the invention, then, comprises the :ieatures hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing the sole figure is a side elevational schematic view of apparatus in accordance with the invention.

The sample to be determined as to sulphur, is

(contained in a combustion boat of usual charcombustion furnace '5 and leads by suitable connection, to an absorption unit 5 wherein the gaseous stream bubbles into a hydrogen peroxide solution. The structure of the furnace 5 may be of customary character, such as with in lusion of suitable electric heating means. The heater 4 however. is peculiar, in involving a heating coil 1 about the Quartz tube 3, and this coil is supplied from a 110 volt line 8 through a variable or regulable winding 9 acro s the line and connected virtually in autotransformer form, by reason of having its movable contact member l0 connected to one end of the heating coil 1, while the other end of the coil is connected to the line. The movable contact I0 is moved over the tap-contacts of the winding. Thus, when the movable contact I0 is at the position shown in the drawing for example, all of the winding 9 is out, but as the contact is moved along over the successive winding contacts, the value of the transformer winding in circuit is progressively increased to maximum. The movable contact is driven-at a constant low speed, its operating shaft H, suitably insulated from the contact [0, being driven by a constant speed motor l2 through a high ratio reduction gear l3. The ratio here may be as desired. A ratio of 200 to 1, or at least to l is satisfactory, or for example the shaft ll may be rotated at a rate to make a revolution in the heating time desired. Acontrol rheostat I may be included in'the motor circuit to permit adjustment to the basal speed desired. The constant speed motor then will maintain this set rate. The control switch, with an operating handle 15 on a short-throwrocker-shaft, is illustrated with contacts I B and I8,ior respective circuits. The switch arm for contact 16 is shown in oii position (solid line). When the handle is rocked to the right (dotted line position) the switch arm is turned (to dotted line position) on the contact is, and this closes the circuit'20, -2 l, 22, from the line through the motor [2, and the reduction gear l3 starts theshaft H in slow motion. The moving contact l0 then starts the transformer and progressively cuts in more and more of the transformer winding 9 to full, in a period for example of thirty minutes. Usually it is preferred that in addit on to the heating which the sample in the boat in has thus received, there should be a further period .of live minutes, for example, of continued maximum heating. One way oiproviding this is by a cam-pin 25 on the shaft H which at the "time the moving contact l9 is'about'ready to leave the last contact on winding -9 reaches the spring-arm switch 26 and closes it, to putthe full 'linecurrent on through 27, 28. This switch is held closed by the campoint 25 for five minutes, for example, while the shaft H completes its rotation, back to zero, and the cam-pin leaves and releases the spring switch 26 and the heat goes off. At the same time, a cam-pin 39 on shaft H comes against the rear extension of the switch arm and rocks it (from the dotted line position to full line position) .to contact l8 and the other switch arm is thrown away from contact It to sto the motor [2. The timing is such that switch 25 opens before contact it! closes on winding 9, and there will be no short circuit. The switch arm now on contact [8 closes a circuit through 22, 32 to a signalbuzzer 33. The operator then opens the normally closed switch 34 to silence the buzzer 33. The operator then opens the normally closed switch 3 34 to silence the buzzer. And the control means is ready for another cycle.

As seen, such equipment subjects the sample in the boat b to a precisely controlled progressing temperature, as the constant speed motor gradually moves the movable contact to allow more and more current to flow through the heating coil 7. The temperature increment being regular and exact, the sample in the combustion boat is evenly and quietly vaporized, with a precision which is the same in all cases. Flashing, and spattering on the tube walls is wholly eliminated, and as the operation is entirely automatic, the chemist is freed from the necessity of keeping close watch on the apparatus, and can go about his other activities.

To determine sulphur for instance in a lubrieating oil, a desired amount of oil is placed in a combustion boat and the boat is inserted into the tube 3, and the absorption unit 6 having been charged with hydrogen peroxide solution the motor is started by closing switch !5. The apparatus then, without further attention, progressively raises the temperature in the heating coil 1 to 700-800" F., over a period for example, of up to 30 minutes, and then maintains full heat for five minutes for example. The vapors passing on through the higher temperature furnace 5, e. g. 1900-2000 F., the sulphur is oxidized to $02, and this is absorbed in the absorption unit 5. The sulphur content of this is then, in the form of sulphate, determined by usual volumetric or gravimetric means.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, 'or th equivalent of such, be employed.

I therefore particularly point out and distinctly claim as m invention:

1. In apparatus of the character described, a combustion furnace, a hot tube leading thereto for containing a combustion boat, and means for heating the tube, including an electric heater, a

variable winding in autotransformer manner.

having one terminal connected to the electric heater and also connected to a supply line and the other terminal of the electric heater connected to a movable contactor for the transformer winding, a shaft and a high ratio reduction gear for moving said movable contactor, a constant speed motor connected to the reduction gear, a switch operated by said shaft for supplying line current for a predetermined time to said heater after the movable contactor cuts out the transformer winding, and. means sequentially operated by said shaft for stopping said motor and signalling the conclusion of the heating.

2. In apparatus of the character described, a combustion furnace, a hot tube leading thereto for containing a combustion boat, and means for heating the tube, including an electric heater, a

variable winding in autotransformer manner former winding, low speed means for moving said contactor to connect said transformer winding to the tube heating means progressively from zero to its full limit and correspondingly raise ,4 the heat on said tube and moving other means to sequentially supply current beyond said transformer capacity direct from th line for a predetermined time and finally cut off the current and signal the conclusion.

3. In apparatus of the character described, a combustion furnace, a quartz tube leading thereto for containing a combustion boat, and an electric heater for supplying heat to vaporize material in such combustion boat, a variable winding in autotransformer manner connected to a supply line and having one terminal connected to said heater and also connected to a supply line and the other terminal of the electric heater connected to a movable contactor for the transformer winding, a high ratio reduction gear for moving said movable contactor to gradually switch in the transformer winding from zero to maximum, and a constant speed motor connected to the reduction gear.

4. In analytical apparatus for sulphur wherein a liquid sample is vaporized, a combustion boat in a hot tube, electric means for heating said tube, and means for preventing boil-over and spattering on the tube, including a regulable transformer heating circuit, slow constant speed motor means gradually increasing the transformer current-input to said tube heating means from zero to maximum of said transformer heating circuit, and a switch operated icy-said motor means sequentially to supply full line current directly to said electric heating means.

5. In apparatus of the character described, a combustion furnace, a hot tube leading thereto for containing a combustion boat, an electric heater for said tube and means for controlling the heater by progressive increment to vaporize material in such combustion boat, including a reduction gear and constant speed motor gradually switching in the heating current for the hot tube from nothing to the maximum of the control means, and a switch operated by said motor sequentially to substitute full line current directly to said electric heater by cutting out the controlling means.

HENRY J. KUSA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES rwrnrrrs- Number Name Date 1,798,678 Keller Mar. 31, 1931 1,861,472 Glitzke June 7, 1932 2,014,926 Buckingham et a1. Sept. 17,1935 2,325,094 Ashworth 1 July 27, 1943 2,344,820 Kearsley Mar. 21, 1944 OTHER REFERENCES Warren: Laboratory Apparatus for Producing a Controlled Temperature Program; Industrial and Engineering Chemistry; Analytical Edition; vol. 5; 1933; p 285, 286.

Tunnicliff et al.: Determination of Carbon and Hydrogen by Combination; Industrialand Engineering Chemistry; Analytical Edition; vol. 18; 1946; pp. 710-718.

Catalog No. 50, Schaar and Co., Chicago. Ill., May 1950, page 313. 

5. IN APPARATUS OF THE CHARACTER DESCRIBED, A COMBUSTION FURNACE, A HOT TUBE LEADIDNG THERETO FOR CONTAINING A COMBUSTION BOAT, AN ELECTRIC HEATER FOR SAID TUBE AND MEANS FOR CONTROLLING THE HEATER BY PROGRESSIVE INCREMENT TO VAPORIZE MATERIAL IN SUCH COMBUSTION BOAT, INCLUDING A REDUCTION GEAR AND CONSTANT SPEED MOTOR GRADUSALLY SWITCHING IN THE HEATING CURRENT FOR THE HOT TUBE FROM NOTHING TO THE MAXIMUM OF THE CONTROL MEANS, AND A SWITCH OPERATED BY SAID MOTOR SEQUENTIALLY TO SUBSTITUTE FULL LINE CURRENT DIRECTLY TO SAID ELECTRIC HEATER BY CUTTING OUT THE CONTROLLING MEANS. 